AB1850 MICROSCOPIC POLYANGIITIS WITH CONCURRENT THROMBOTIC THROMBOCYTOPENIC PURPURA: A CASE REPORT
Authors: E. Tullis, C. Roy, J. Petkova
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Thrombotic thrombocytopenic purpura (TTP) and Microscopic polyangiitis (MPA) rarely occur in conjunction. Autoimmune TTP is caused by autoantibodies to the ADAMTS13 protein that cleaves von Willebrand factor. MPA is a small-vessel vasculitis that typically affects the small blood vessels of the lung and kidney [1]. We present a case of concurrent TTP and MPA which we believe could highlight a pathogenetic correlation and treatment overlap between the two diseases. <h3>Objectives</h3> To report a rare case of concurrent TTP and MPA and to educate physicians on optimal treatment strategies. <h3>Methods</h3> Case report and literature review. <h3>Results</h3> A 67-year-old patient with history of stroke and sickle cell trait presented to the emergency department due to altered mental status and fever. Serology on admission was notable for marked acute kidney injury and anemia requiring transfusions. Urinalysis showed hematuria and proteinuria. Autoimmune serology was remarkable for p-ANCA positivity at 1:80 with myeloperoxidase antibody &gt; 30 pmol/L; a diagnosis of MPA was made. Patient's serology was also remarkable for thrombocytopenia with a nadir under 60 and evidence of thrombotic microangiopathy on peripheral blood smear and hemolysis labs. ADAMTS13 autoantibodies were reduced with less than 3% functionality and an inhibitor of 1/0 BU, confirming a concurrent diagnosis of TTP. Patient was initiated on high-dose steroids and therapeutic plasma exchange (TPE) with resultant normalization of platelets and improvement in renal function. TPE was discontinued, and the patient was transitioned to rituximab with continuation of high-dose steroids. The patient was ultimately discharged home with a steroid taper and maintenance rituximab dosing. <h3>Conclusion</h3> Per literature review, three other cases of concurrent TTP and MPA have been reported [2-4]. Further investigation into pathogenetic and treatment overlap of MPA and TTP may be warranted. Although rare, when occurring together the presentation is often severe, and urgent initiation of treatment is critical. TPE is the mainstay of treatment in TTP but is usually only recommended in MPA patients with anti-GBM antibodies, those at high risk of progression to end stage renal disease, or those unresponsive to first-line therapies [1,5,6]. Rituximab, which acts to decrease B cell activity and overall antibody production, has been shown to reduce disease activity in both conditions [1,5]. This case report suggests that, in the rare event that TTP and MPA are concurrently diagnosed, the combined use of rituximab and TPE in conjunction with steroids may induce remission more efficiently than either treatment alone. <h3>References</h3> [1] Chung SA, Langford CA, Maz M, et al. 2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis. <i>Arthritis Rheumatol</i>. 2021. doi:10.1002/art.41773 [2] Hirsch DJ, Jindal KK, Trillo AA. Antineutrophil cytoplasmic antibody-positive crescentic glomerulonephritis and thrombotic microangiopathy. <i>Am J Kidney Dis</i>. 1995. doi:10.1016/0272-6386(95)90663-0 [3] Nagai K, Kotani T, Takeuchi T, et al. Successful treatment of thrombotic thrombocytopenic purpura with repeated plasma exchange in a patient with microscopic polyangitis. <i>Mod Rheumatol</i>. 2008. doi:10.1007/s10165-008-0107-3 [4] Syed Mujtaba Ali Naqvi, Rachel Whittaker, Arti Saraswat, Nisarfarthi Kazimuddin, Rishi Agarwal; A Rare Case of Concurrent New-Onset Microscopic Polyangiitis and Thrombotic Thrombocytopenic Purpura in a 77-Year-Old Woman. Blood 2021. doi: https://doi.org/10.1182/blood-2021-148966 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.